The isolation and purification of esterase 1 from the cytosol of rabbit neutrophils will be pursued further using preparative iso-electric focusing. We will attempt to delineate further the kinds of cellular reactions involving esterase activition, utilizing phosphonate esters, inhibitors and/or direct biochemical measurement of substrate breakdown where indicated. In addition, the nature of the esterases involved and the manner of their action will be studied. In collaboration with Dr. Ramadan I. Sha'afi we will continue our studies of cation transport and function in the neutrophil in relation to such neutrophil functions as stimulated movements induced lysosomal enzyme release. We also will further explore the nature and function of the receptor on the neutrophil membrane that reacts with synthetic oligopeptide chemotactic factors. BIBLIOGRAPHIC REFERENCES: Aswanikumar, S., B. Corcoran, E. Schiffmann, A.R. Day, R.J. Freer, H.J. Showell, E.L. Becker and C. Pert. Demonstration of a receptor on rabbit neutrophils for chemotactic peptides. Biochem. Biophys. Res. Commun. 74:810-817, 1977. P.H. Naccache, H.J. Showell, E.L. Becker and R.I. Sha'afi. Sodium, Potassium and Calcium transport across rabbit polymorphonuclear leukocyte membranes: Effect of chemotactic factor. J. Cell Biol. 73:428-444, 1977.